Process control systems typically employ a variety of field devices to monitor and control the flow of fluids. These field devices operate to detect, assess and/or alter various fluid parameters (e.g., pressure, temperature, level, etc.) within a process plant or system in order to ensure accurate process control.
One common field device is a liquid level controller, which is typically mounted to a process vessel that holds a fluid or liquid. The liquid level controller includes a rotatable lever assembly that is coupled to a displacer disposed inside the vessel. The displacer moves in response to changes in the fluid or liquid level, and conveys these changes to the controller via changes in the rotational position of the lever assembly.
To protect the liquid level controller from damage during shipment or other handling, an operator needs to prevent the lever assembly from rotating by manually engaging a locking mechanism. The locking mechanism must be disengaged before the liquid level controller is put into operation. However, if the operator forgets or neglects to disengage the locking mechanism, then the lever assembly may fail which in turn may cause the controller to become inoperable.